December 28, 1917] 



SCIENCE 



641 



EFFICIENT LABORATORY LIGHTING 



Several notes have appeared in Science the 

 past few years relative to the development of 

 glass through which a proper spectroscopic cor- 

 rection could be secured for microscopic pur- 

 poses. There are also on the market various 

 microscope lamps designed to furnish a cor- 

 rected artificial light for laboratory study. 



These devices, though very satisfactory for 

 small advanced classes, are in many ways un- 

 desirable for large classes of elementary stu- 

 dents, and sitting, as they usually do, on the 

 laboratory table, are more or less subject to 

 breakage when used by large numbers of stu- 

 dents. 



The dark winter days during a part of the 

 school year made it imperative that the large 

 classes in agricultural botany at Oregon Agri- 

 cultural College be provided with a light which 

 would yield relative daylight values with tem- 

 porary mounts and stained prepared sections. 

 This has been attained most efficiently by the 

 use of the General Electric Company's Ivanhoe 

 Truetint Unit No. 748, known as the "Noon 

 Sunlight " grade. This is a large, apparently 

 blue shade, designed to cover the high-power 

 nitrogen-filled Mazda lamp. Experience has 

 shown that one of these units suspended two 

 feet above the laboratory table and equipped 

 with a one-hundred-watt bulb gives a superior 

 light for four students. In this way, forty 

 students at one time are being handled with 

 ease on dark days, the illumination being 

 ample even for the high-power dry or the oil 

 immersion objectives. 



The cost of the entire installation is ap- 

 proximately the same for four men as that of 

 the usual microscope lamp designed for one 

 person. To secure a fixture which would be 

 near the table without obstructing it for 

 laboratory work, the shade holders %vere sus- 

 pended by nickel chains from the ceiling over 

 the center of each table. The lack of rigidity 

 of the fixture thus equipped is of special ad- 

 vantage in the elimination of breakage. 



W. M. Atwood 

 Dept. of Botany and Plant Pathology, 

 Okeqon Agricoltdral College 



SCIENTIFIC BOOKS 



The Elements of the Science of Nutrition. 

 Third Edition. By Graham Lusk. Phila- 

 delphia, W. B. Saunders Co., 1917. Pp. 641. 

 It is sometimes said that the sciences and 

 the fine arts are international in the broadest 

 sense of the word; they do not recognize na- 

 tional boundaries or racial limitations. Nev- 

 ertheless a nation may well be concerned about 

 the accomplishments of its citizens in the pur- 

 suit of knowledge. " Knowledge once won," 

 Gowland Hopkins has recently written in a 

 co mm endable essay on medicine and experi- 

 mental science, " is of no country ; it is the 

 common guerdon of mankind; but he who 

 cares nothing as to where it grows seems to 

 lack an element of patriotism." 



From this standpoint American science 

 need not be dissatisfied with the contributions 

 which the workers in this country have made 

 to the study of nutrition in the past decade. 

 Lusk's " Science of Nutrition," which has 

 established itself as a stimulating and com- 

 prehensive text-book, discloses the names of 

 more than one hundred American investigators 

 whose labors have helped, probably in larger 

 measure than those of any other country, to 

 bring new facts and permit new viewpoints in 

 nutrition during the interval that has elapsed 

 since the earlier (1909) edition of the book. 

 Its size has been expanded from 400 to 600 

 pages not by the mere accretion of incidental 

 observations but by the addition of carefully 

 considered novelties which the later develop- 

 ment seems to warrant as worthy of consid- 

 eration. 



The style and mode of treatment of the 

 problems of nutrition remain essentially un- 

 changed in the new edition. The historical 

 method has been followed in a way that can 

 not fail to interest those who are more fa- 

 miliar with the subject-matter, and that ought 

 to enthuse the beginner. There is something 

 almost inspiring in following the story from 

 its beginnings in the days of Lavoisier down 

 to the ingenious contrivances for respiration 

 study and calorimetry so highly developed in 

 the university laboratories and research in- 



